The invention relates to a bearing comprising two parts which are rotatable relative to each other, and having facing bearing surfaces which cooperate with each other on the respective parts, one or both surfaces including one or more patterns of shallow, parallel lubricant pumping grooves.
A bearing of the kind which is the subject of the present invention is known from British Patent Specification No. 1,068,448. This known bearing is an axial bearing suitable for two directions of rotation, because the cooperating bearing surfaces are provided with two patterns of grooves, one pattern having a pumping effect in the case of rotation in one direction, and the other pattern having a pumping effect upon rotation in the other direction. The patterns therein are separated from each other by a zone in which lubricant is supplied for one of the patterns of grooves. When lubricant is continuously supplied to the patterns, this bearing is very suitable for two directions of rotation, but if the bearing is not relubricated, as for example when the bearing is filled once with grease, this bearing will discharge all of its lubricant after a very brief period of time, so that further operation is not possible.
A radial bearing having two patterns of grooves on the cooperating surfaces is known from United States Patent Specification No. 3,467,449 and British Patent Specification No. 1,022,391. Therein, the two patterns of grooves pump against each other in one direction of rotation, so that pressure is built up. Rotation in the other direction is not permissible, because no pumping action occurs and hence no pressure is built up.